Published 2021-06-15 · Federal Register document 2021-12435
Airworthiness Directives; De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.) Airplanes
Publication summary
The FAA is adopting a new airworthiness directive (AD) for certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes. This AD was prompted by a report that a number of nacelle A- frames were not manufactured in accordance with engineering drawings. This AD requires, depending on airplane configuration, removing the fasteners on the nacelle A-frame side brace sub-assemblies, doing an eddy current inspection for cracking, cold-working the holes, installing oversize fasteners, re-identifying the reworked side brace fitting and A-frame, and repair if necessary. The FAA is issuing this AD to address the unsafe condition on these products.
Why this record is shown
Source: Federal Register annual FAA metadata. Acquired 2026-09-03T22:24:08.106391+00:00. The title, summary and date are source facts.
- Source revision
- federal_register_ad_metadata_2021-9c919420683447c6
- Source row
- results[204]
- Raw source SHA-256
- 9c919420683447c683ad0c877cb886e341c11862be32b47c536a001b1d76dcb5
Final-rule publication
Recorded publication clauses
- AD identifier printed in this edition
- 2021-12-02
- Effective date printed in this edition
- 2021-07-20
Read 10 complete recorded clauses
Effective Date
(a) Effective Date
This airworthiness directive (AD) is effective July 20, 2021.
Exact source excerpt. Text positions 9591–9678, end exclusive, in the original decoded publication. SHA-256: f0ad72088eac26712afb17ab2c8d07711caabdfb4faf46098530edf5f53508b7
Affected ADs
(b) Affected ADs
None.
Exact source excerpt. Text positions 9678–9707, end exclusive, in the original decoded publication. SHA-256: 871a4afc60ceeae06e8010585055188633d616078500c45937092bfe892239c0
Applicability wording · Applicability
(c) Applicability
This AD applies to De Havilland Aircraft of Canada Limited (type
certificate previously held by Bombardier, Inc.) Model DHC-8-400, -
401, and -402 airplanes, certificated in any category, serial
numbers 4081 through 4591 inclusive.
Exact source excerpt. Text positions 9707–9965, end exclusive, in the original decoded publication. SHA-256: 57ebf77374a580654f3f728fc9d3f6d9a15322abb769b6f5032f3c4f4d7283aa
Subject
(d) Subject
Air Transport Association (ATA) of America Code 54, Nacelles/
pylons.
Exact source excerpt. Text positions 9965–10053, end exclusive, in the original decoded publication. SHA-256: 965d2e1891bda21636b3e8a29c4a3b1fe986ee773e61af574cd84217708deb41
Reason
(e) Reason
This AD was prompted by a report that a number of nacelle A-
frames were not manufactured in accordance with engineering
drawings. The holes in the side brace sub-assemblies were not cold-
worked as required. As a result the side brace fitting might not
meet its fatigue life, and cracking of the A-frame bottom flange may
result. The FAA is issuing this AD to address possible cracking of
the A-frame. This condition, if not addressed, may lead to collapse
of the main landing gear (MLG).
Exact source excerpt. Text positions 10053–10565, end exclusive, in the original decoded publication. SHA-256: cbb7b489481801e2fda9b65fba73b199824d53abfd3f33161c4c35f767e6b06d
Compliance
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
Exact source excerpt. Text positions 10565–10667, end exclusive, in the original decoded publication. SHA-256: 00fbfa31932483f627d0ce0a11cbd2e35e15d9231842b91ac85623ce533912d3
Required Actions
(g) Required Actions
(1) Within the compliance time specified in paragraph (g)(2) of
this AD, do the applicable actions specified in paragraphs (g)(1)(i)
and (ii) of this AD.
(i) For airplanes having serial numbers 4081 through 4582
inclusive: Remove the fasteners on the nacelle A-frame side brace
sub-assemblies, do an eddy current inspection for cracking on
airplanes having 30,000 total flight cycles or more, cold-work the
holes, and install oversize fasteners, in accordance with Part A of
paragraph 3.B. of the Accomplishment Instructions of De Havilland
Aircraft of Canada Limited Service Bulletin 84-54-32, dated October
10, 2019. If any cracking is found, before further flight, repair
the cracking using a method approved by the Manager, New York ACO
Branch, FAA; or Transport Canada Civil Aviation (TCCA); or De
Havilland Aircraft of Canada Limited's TCCA Design Approval
Organization (DAO). If approved by the DAO, the approval must
include the DAO-authorized signature.
(ii) For all airplanes: Re-identify the reworked side brace
fitting and A-frame, in accordance with Part B of paragraph 3.B. of
the Accomplishment Instructions of De Havilland Aircraft of Canada
Limited Service Bulletin 84-54-32, dated October 10, 2019.
(2) At the earlier of the times specified in paragraphs
(g)(2)(i) and (ii) of this AD, do the applicable actions specified
in paragraph (g)(1) of this AD.
(i) Within 48 months or 8,000 flight hours after the effective
date of this AD, whichever occurs first.
(ii) At the later of the times specified in paragraphs
(g)(2)(ii)(A) and (B) of this AD.
(A) Before accumulating 40,000 total flight cycles.
(B) Within 12 months or 1,290 flight cycles after the effective
date of this AD, whichever occurs first.
Exact source excerpt. Text positions 10667–12466, end exclusive, in the original decoded publication. SHA-256: 9a80ba4b111153213481c0690a24363539d361fee97fb9aa63c826c646e9d7e4
Other FAA AD Provisions
(h) Other FAA AD Provisions
The following provisions also apply to this AD:
(1) Alternative Methods of Compliance (AMOCs): The Manager, New
York ACO Branch, FAA, has the authority to approve AMOCs for this
AD, if requested using the procedures found in 14 CFR 39.19. In
accordance with 14 CFR 39.19, send your request to your principal
inspector or responsible Flight Standards Office, as appropriate. If
sending information directly to the manager of the certification
office, send it to ATTN: Program Manager, Continuing Operational
Safety, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; telephone 516-228-7300; fax 516-794-5531. Before
using any approved AMOC, notify your appropriate principal
inspector, or lacking a principal inspector, the manager of the
responsible Flight Standards Office.
(2) Contacting the Manufacturer: For any requirement in this AD
to obtain instructions from a manufacturer, the instructions must be
accomplished using a method approved
[[Page 31601]]
by the Manager, New York ACO Branch, FAA; or TCCA; or De Havilland
Aircraft of Canada Limited's TCCA DAO. If approved by the DAO, the
approval must include the DAO-authorized signature.
Exact source excerpt. Text positions 12466–13698, end exclusive, in the original decoded publication. SHA-256: 541a80373ba72175e5687fad5e6b25d7ed3041c935646544c74402b7f877dfad
Related Information
(i) Related Information
(1) Refer to Mandatory Continuing Airworthiness Information
(MCAI) TCCA AD CF-2020-39, dated October 14, 2020, for related
information. This MCAI may be found in the AD docket on the internet
at https://www.regulations.gov by searching for and locating Docket
No. FAA-2021-0183.
(2) For more information about this AD, contact Antariksh
Shetty, Aerospace Engineer, Airframe and Propulsion Section, FAA,
New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; telephone 516-228-7300; fax 516-794-5531; email [email protected].
Exact source excerpt. Text positions 13698–14282, end exclusive, in the original decoded publication. SHA-256: 1606209f95b2f0f8b2d094ed900bd180bd72e3eea2d7a261595ddaf01d2a306c
Material Incorporated by Reference
(j) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference (IBR) of the service information listed
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do
the actions required by this AD, unless this AD specifies otherwise.
(i) De Havilland Aircraft of Canada Limited Service Bulletin 84-
54-32, dated October 10, 2019.
(ii) [Reserved]
(3) For service information identified in this AD, contact De
Havilland Aircraft of Canada Limited, Q-Series Technical Help Desk,
123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone
416-375-4000; fax 416-375-4539; email [email protected]; internet
https://dehavilland.com.
(4) You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 2200
South 216th St., Des Moines, WA. For information on the availability
of this material at the FAA, call 206-231-3195.
(5) You may view this service information that is incorporated
by reference at the National Archives and Records Administration
(NARA). For information on the availability of this material at
NARA, email [email protected], or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.
Exact source excerpt. Text positions 14282–15609, end exclusive, in the original decoded publication. SHA-256: 32099e24d2196522572b60a1a459810aeb5201b122d4dda29eadec4ddf06356b
No replacement link has been established from this edition. The complete historical rule chain and current legal effect remain unknown.
Find all recorded historical references to AD 2021-12-02 · 0 printed reference observations in this pinned collection.
These are observations from one dated publication. Current legal status is unknown; aircraft applicability, installed configuration, compliance and burden require separate evidence. Missing or unparsed conditions remain unknown.
Why these observations are shown
They were extracted offline from the same immutable official HTML source as the complete recorded text. The dated source wording, original text coordinates and exact quote digests are retained. PDF/text agreement and current regulatory effect have not been qualified.
Observation revision: whole-ad-publication-clause-observations-1.0.1. Text SHA-256: 2d73c19f04c8465bcf3758481be50048099b017bbdb6368c35cba6fcca059a94. Source manifest: 8116ebe950b6dc3202e722cb27bf3601c8dbba0c0c86e677b2ef1a5cf4018b9b.
Official source · 2021-06-15
Publication text
This is the complete recorded text of this dated publication.
Current legal effect is unknown. Aircraft applicability, installed configuration and compliance require separate evidence. PDF/text agreement has not been evaluated.
Read the complete official publication text
[Federal Register Volume 86, Number 113 (Tuesday, June 15, 2021)]
[Rules and Regulations]
[Pages 31599-31601]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-12435]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-0183; Project Identifier MCAI-2020-01408-T;
Amendment 39-21589; AD 2021-12-02]
RIN 2120-AA64
Airworthiness Directives; De Havilland Aircraft of Canada Limited
(Type Certificate Previously Held by Bombardier, Inc.) Airplanes
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series
airplanes. This AD was prompted by a report that a number of nacelle A-
frames were not manufactured in accordance with engineering drawings.
This AD requires, depending on airplane configuration, removing the
fasteners on the nacelle A-frame side brace sub-assemblies, doing an
eddy current inspection for cracking, cold-working the holes,
installing oversize fasteners, re-identifying the reworked side brace
fitting and A-frame, and repair if necessary. The FAA is issuing this
AD to address the unsafe condition on these products.
DATES: This AD is effective July 20, 2021.
The Director of the Federal Register approved the incorporation by
reference of certain publication listed in this AD as of July 20, 2021.
ADDRESSES: For service information identified in this final rule,
contact De Havilland Aircraft of Canada Limited, Q-Series Technical
Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada;
telephone 416-375-4000; fax 416-375-4539; email [email protected];
internet https://dehavilland.com. You may view this service information
at the FAA, Airworthiness Products Section, Operational Safety Branch,
2200 South 216th St., Des Moines, WA. For information on the
availability of this material at the FAA, call 206-231-3195. It is also
available on the internet at https://www.regulations.gov by searching
for and locating Docket No. FAA-2021-0183.
Examining the AD Docket
You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-
0183; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this final rule, any comments received, and other information. The
address for Docket Operations is U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT: Antariksh Shetty, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7300; fax 516-
794-5531; email [email protected].
SUPPLEMENTARY INFORMATION:
Background
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2020-39, dated October 14,
2020 (TCCA AD CF-2020-39) (also referred to as the Mandatory Continuing
Airworthiness Information, or the MCAI), to correct an unsafe condition
for certain De Havilland Aircraft of Canada Limited Model DHC-8-400
series airplanes. You may examine the MCAI in the AD docket on the
internet at https://www.regulations.gov by searching for and locating
Docket No. FAA-2021-0183.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain De Havilland
Aircraft of Canada Limited Model DHC-8-400 series airplanes. The NPRM
published in the Federal Register on March 22, 2021 (86 FR 15149). The
NPRM was prompted by a report that a number of nacelle A-frames were
not manufactured in accordance with engineering drawings. The holes in
the side brace sub-assemblies were not cold-worked as required. As a
result the side brace fitting might not meet its fatigue life, and
cracking of the A-frame bottom flange may result. The NPRM proposed to
require, depending on airplane configuration, removing the fasteners on
the nacelle A-frame side brace sub-assemblies, doing an eddy current
inspection for cracking, cold-working the holes, installing oversize
fasteners, re-identifying the reworked side brace fitting and A-frame,
and repair if necessary. The FAA is issuing this AD to address possible
cracking of the A-frame. This condition, if not addressed, may lead to
collapse of the main landing gear (MLG). See the MCAI for additional
background information.
Comments
The FAA gave the public the opportunity to participate in
developing this final rule. The FAA has considered the comment
received. The Air Line Pilots Association, International (ALPA), stated
that it supports the NPRM.
Conclusion
The FAA reviewed the relevant data, considered the comment
received, and determined that air safety and the public interest
require adopting this final rule as proposed, except for minor
editorial changes. The FAA has determined that these minor changes:
<bullet> Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
<bullet> Do not add any additional burden upon the public than was
already proposed in the NPRM.
Related Service Information Under 1 CFR Part 51
De Havilland Aircraft of Canada Limited has issued Service Bulletin
84-54-32, dated October 10, 2019. This service information describes
procedures, depending on airplane configuration, for removing the
fasteners on the nacelle A-frame side brace sub-assemblies, doing an
eddy current inspection for cracking, cold-working the holes,
installing oversize fasteners, and re-identifying the reworked side
brace fitting and A-frame.
This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in the ADDRESSES section.
Costs of Compliance
The FAA estimates that this AD affects 41 airplanes of U.S.
registry. The
[[Page 31600]]
FAA estimates the following costs to comply with this AD:
Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
15 work-hours x $85 per hour = $1,275........................ $254 $1,529 $62,689
----------------------------------------------------------------------------------------------------------------
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
0
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
2021-12-02 De Havilland Aircraft of Canada Limited (Type Certificate
Previously Held by Bombardier, Inc.): Amendment 39-21589; Docket No.
FAA-2021-0183; Project Identifier MCAI-2020-01408-T.
(a) Effective Date
This airworthiness directive (AD) is effective July 20, 2021.
(b) Affected ADs
None.
(c) Applicability
This AD applies to De Havilland Aircraft of Canada Limited (type
certificate previously held by Bombardier, Inc.) Model DHC-8-400, -
401, and -402 airplanes, certificated in any category, serial
numbers 4081 through 4591 inclusive.
(d) Subject
Air Transport Association (ATA) of America Code 54, Nacelles/
pylons.
(e) Reason
This AD was prompted by a report that a number of nacelle A-
frames were not manufactured in accordance with engineering
drawings. The holes in the side brace sub-assemblies were not cold-
worked as required. As a result the side brace fitting might not
meet its fatigue life, and cracking of the A-frame bottom flange may
result. The FAA is issuing this AD to address possible cracking of
the A-frame. This condition, if not addressed, may lead to collapse
of the main landing gear (MLG).
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) Within the compliance time specified in paragraph (g)(2) of
this AD, do the applicable actions specified in paragraphs (g)(1)(i)
and (ii) of this AD.
(i) For airplanes having serial numbers 4081 through 4582
inclusive: Remove the fasteners on the nacelle A-frame side brace
sub-assemblies, do an eddy current inspection for cracking on
airplanes having 30,000 total flight cycles or more, cold-work the
holes, and install oversize fasteners, in accordance with Part A of
paragraph 3.B. of the Accomplishment Instructions of De Havilland
Aircraft of Canada Limited Service Bulletin 84-54-32, dated October
10, 2019. If any cracking is found, before further flight, repair
the cracking using a method approved by the Manager, New York ACO
Branch, FAA; or Transport Canada Civil Aviation (TCCA); or De
Havilland Aircraft of Canada Limited's TCCA Design Approval
Organization (DAO). If approved by the DAO, the approval must
include the DAO-authorized signature.
(ii) For all airplanes: Re-identify the reworked side brace
fitting and A-frame, in accordance with Part B of paragraph 3.B. of
the Accomplishment Instructions of De Havilland Aircraft of Canada
Limited Service Bulletin 84-54-32, dated October 10, 2019.
(2) At the earlier of the times specified in paragraphs
(g)(2)(i) and (ii) of this AD, do the applicable actions specified
in paragraph (g)(1) of this AD.
(i) Within 48 months or 8,000 flight hours after the effective
date of this AD, whichever occurs first.
(ii) At the later of the times specified in paragraphs
(g)(2)(ii)(A) and (B) of this AD.
(A) Before accumulating 40,000 total flight cycles.
(B) Within 12 months or 1,290 flight cycles after the effective
date of this AD, whichever occurs first.
(h) Other FAA AD Provisions
The following provisions also apply to this AD:
(1) Alternative Methods of Compliance (AMOCs): The Manager, New
York ACO Branch, FAA, has the authority to approve AMOCs for this
AD, if requested using the procedures found in 14 CFR 39.19. In
accordance with 14 CFR 39.19, send your request to your principal
inspector or responsible Flight Standards Office, as appropriate. If
sending information directly to the manager of the certification
office, send it to ATTN: Program Manager, Continuing Operational
Safety, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; telephone 516-228-7300; fax 516-794-5531. Before
using any approved AMOC, notify your appropriate principal
inspector, or lacking a principal inspector, the manager of the
responsible Flight Standards Office.
(2) Contacting the Manufacturer: For any requirement in this AD
to obtain instructions from a manufacturer, the instructions must be
accomplished using a method approved
[[Page 31601]]
by the Manager, New York ACO Branch, FAA; or TCCA; or De Havilland
Aircraft of Canada Limited's TCCA DAO. If approved by the DAO, the
approval must include the DAO-authorized signature.
(i) Related Information
(1) Refer to Mandatory Continuing Airworthiness Information
(MCAI) TCCA AD CF-2020-39, dated October 14, 2020, for related
information. This MCAI may be found in the AD docket on the internet
at https://www.regulations.gov by searching for and locating Docket
No. FAA-2021-0183.
(2) For more information about this AD, contact Antariksh
Shetty, Aerospace Engineer, Airframe and Propulsion Section, FAA,
New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; telephone 516-228-7300; fax 516-794-5531; email [email protected].
(j) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference (IBR) of the service information listed
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do
the actions required by this AD, unless this AD specifies otherwise.
(i) De Havilland Aircraft of Canada Limited Service Bulletin 84-
54-32, dated October 10, 2019.
(ii) [Reserved]
(3) For service information identified in this AD, contact De
Havilland Aircraft of Canada Limited, Q-Series Technical Help Desk,
123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone
416-375-4000; fax 416-375-4539; email [email protected]; internet
https://dehavilland.com.
(4) You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 2200
South 216th St., Des Moines, WA. For information on the availability
of this material at the FAA, call 206-231-3195.
(5) You may view this service information that is incorporated
by reference at the National Archives and Records Administration
(NARA). For information on the availability of this material at
NARA, email [email protected], or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.
Issued on May 25, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification
Service.
[FR Doc. 2021-12435 Filed 6-14-21; 8:45 am]
BILLING CODE 4910-13-P
Why this text is shown
The complete text was extracted from the official GovInfo HTML edition for this publication. Acquired 2026-10-09T01:50:39.272833+00:00. Text extraction preserves the recorded source wording; it does not determine current requirements.
Open the captured official edition
- Source SHA-256
- ab4e7252be72c7d9109472932aa0f3d4b588ecab9cf7a49aa0658536107da766
- Text SHA-256
- 2d73c19f04c8465bcf3758481be50048099b017bbdb6368c35cba6fcca059a94
Return to the full metadata catalog · Search complete publication text · Explore retained publication text and evidence
Coverage and limits
These are dated publication metadata, recorded clauses and literal source observations. Word, model-label, header and reference matches do not establish current legal effect, manufacturer/model identity, aircraft applicability, installed configuration or compliance.
The collection uses 33 explicit annual source snapshots. Source captures and operative-text qualifications have separate states. Missing information remains unknown.